Hydraulic laundry machine transmission



June 30, 1970 R. w. BRUNDAGE 3,517,507

HYDRAULIC LAUNDRY MACHINE TRANSMISSION Filed June 5, 1968 4 Sheets-Sheet 1 FIG. I

D SPIN "rs AGITATE F 32 INVENTOR- ROBERT W. BRUNDAGE 3&0, 7M 8 M,

ATTORNEYS June 30, 1970 R. w. BRUNDAGE 3,517,507

HYDRAULIC LAUNDRY MACHINE TRANSMISSION 4 Sheets-Sheet 2 Filed June 5, 1968 INVENTOR. ROBERT W. BRUNDAGE BY Maym,7d%mq 8 Bad,

ATTORNEYS June 30, 1970 R. w. BRUNDAGE 9 HYDRAULIC LAUNDRY MACHINE TRANSMISSION 4 Sheets-Sheet 5 Filed June 5. 1968 INVENTOR- ROBERT w. BRUNDAGE ATTORNEYS June 30, 1970 R. w. BRUNDAGE 3,517,507

HYDRAULIC LAUNDRY MACHINE TRANSMISSION Filed June 5, 1968 4 SheecsSheet 4 FIG. 7

\ INVENTOR.

/ RQBERT W- BRUNDAGE MW, 7% 8 od;

ATTORNEYS United States Patent 3,517,507 HYDRAULIC LAUNDRY MACHINE TRANSMISSION Robert W. Brundage, St. Louis, Mo., assiguor to Emerson Electric Company, St. Louis, Mo., a corporation of Missouri Filed June 5, 1968, Ser. No. 734,650 Int. Cl. D06f 29/00; F15!) 15/18 U.S. Cl. 60-52 9 Claims ABSTRACT OF THE DISCLOSURE A hydraulic transmission for laundry machines of the agitate-spin type. The transmission has an outer housing mounted for and held against rotation by a normally engaged brake which is released by a hydraulic piston cylinder arrangement. The transmission includes a positive displacement hydraulic pump which when rotated in one direction supplies hydraulic fluid to a vane type oscillating motor coupled to the agitator. When the pump is rotated in the opposite direction, it supplies fluid to the piston cylinder arrangement to release the brake. When the piston cylinder arrangement will not accept any more fluid from the pump, the pump becomes a slip clutch and drives the transmission housing to rotate the spin basket. A relief valve biased closed by a spring limits the maximum torque as the spin cycle starts. The valve member moves on a radial line and centrifugal force biases it against the spring so as to reduce the maximum opening pressure as the speed of rotation increases. This effectively limits the top speed of the spin cycle in the event of oif balance.

This invention pertains to the art of hydraulic power transmissions and more particularly to a hydraulic power transmission capable of accepting rotary motion and selectively driving either of a pair of rotating members.

The invention is particularly applicable to a power transmission for a laundry machine of the type which both agitates and spin dries the laundry and will be described with particular reference thereto although it will be appreciated that the invention has other and broader applications.

BACKGROUND Such laundry machines generally comprise a large tub fixed against rotation, a rotatable perforated basket within the tub, and an agitator within the basket. The tub holds water to a predetermined level, while the basket supports the clothes submerged in the water. The agitator is oscillated at somewhere between 20 and 100 oscillations per minute and continuously moves the clothes to be washed back and forth through the water. After the clothes have been agitated a suflicient length of time, the water is pumped or allowed to drain out of the tub and the basket is then spun at speeds of between 50 and 800 r.p.m. to force the water out of the clothes by centrifugal action. The process or variations thereof may then be repeated for any number of cycles.

Such laundry machines have normally been powered by an electric motor rotating at a nominal speed of 1800 r.p.m. Belts, pulleys, and/or multiple gear trains and crank arms have been required in the past to reduce the rotational speed of the motor to the oscillating speed of the agitator and then to change the rotational motion of the motor to the oscillating or reciprocating action required by the agitator. In addition to this, friction clutches, electrical solenoids to operate the clutches, brakes and electrical solenoids to operate the brakes have been required to shift from the spin cycle to the oscillating cycle or vice versa.

ice

Such mechanical transmissions are expensive to manufacture, cumbersome in size, diflicult to lubricate, wear out rapidly, become noisy and ditficult to maintain or repair.

Furthermore, unless the clutches are provided with a neutral position or are centrifugally operated, either of which is expensive, the motor is required to start under a heavy load, requiring the use of a more expensive high starting torque motor rather than the less expensive low starting torque types such as split phase types.

One solution to these problems was suggested in my Pat. No. 3,242,703 issued Mar. 29, 1966. In this patent an electric motor which could be energized to rotate in either direction drove a positive displacement hydraulic pump. The output of the pump flowed relatively freely past a valve member in a neutral position which flow shifted the valve automatically in either direction depending on the direction of rotation of the pump, such that: when the pump was driven in one direction, the valve member moved to direct the flow of fluid from the pump to a vane type oscillating motor; and when the pump was driven in the opposite direction, the valve member shifted to direct the pump output fluid to a rotating type hy draulic motor which then drove the spin basket. In this case the transmission housing remained stationary at all times.

Pat. No. 2,574,418 issued Nov. 6, 1951 to Rubano suggested an alternative approach wherein a unidirectional electric motor drove a first positive displacement bydraulic pump which pumped hydraulic fluid to a vane type hydraulic motor which then drove the agitator. During the agitate cycle the housing of the pump and vane motor were held against rotation by means of a normally engaged friction brake. When it was desired to spin the clothes basket, a pair of solenoid actuated valves were actuated; one to connect the output of the pump to the sump so that the agitate motor was no longer supplied with fluid, and to block the discharge of the second hydraulic pump so that its output was supplied to a bellows arrangement which released the friction brake. The electric motor then drove the outer housing of the first pump and vane motor through a slip type fluid coupling to cause the spin basket to rotate. Such mechanism required two pumps, two solenoid operated valves and a fluid coupling which were not only expensive to build but also cumbersome and mechanically inefl'icient.

A still further problem which has existed in such machines is in limiting the spin speed when the clothes in the spin basket are not symmetrically located around the spin axis. In such instances, if the speed goes to the maximum, serious damage can result to the machine.

SUMMARY OF THE INVENTION The present invention contemplates a transmission of a general type described which overcomes all of the above referred to difliculties and others, and provides a transmission particularly adaptable for laundry machines which is inexpensive to manufacture, is simple in construction, enables a simple split phase type motor to be employed, is fully self-contained and entirely automatic in operation.

In accordance with the broadest aspect of the present invention, a hydraulic transmission is provided particularly adapted for laundry machines of the spin-agitate type comprised of: a housing rotatable on an axis and adapted to be operatively associated with a spin basket; a motor within the housing adapted to be operatively associated with an agitator; and a positive displacement hydraulic pump Within the housing driven by a shaft rotatable on the same axis as the housing and means within the housing communicating the discharge of said pump selectively to either: the motor or a closed chamber which blocks the discharge of the pump whereby the pump acts as a slip clutch and transmits the torque on its drive shaft to the housing and rotates it.

In a further aspect of the invention, the hydraulic pump is bidirectional and when rotating in one direction supplies hydraulic fluid to the motor and when rotating in the opposite direction has its output at least in part blocked whereby the pump functions as a slip clutch.

In a still further aspect of the invention, means are provided for restraining the housing from rotation when the pump is supplying fluid to the motor and said means are released when the output of the motor is blocked so that the housing may freely rotate.

In another aspect of the invention the means for restraining the housing from rotation is a normally engaged brake and a hydraulic device of limited hydraulic capacity is provided for releasing the brake which device is communicated with the output of the pump when the output is blocked whereby the pressure in the blocked outlet of the pump will release the brake.

In accordance with a specific aspect of the present invention, a hydraulic transmission is provided particularly adapted for laundry machines, comprised of: a rotatable housing adapted to be operatively associated with a spin basket and restrained from rotation by normally engaged brake but released by a hydraulic device; an oscillating motor within the housing adapted to be operatively associated with the agitator; and a bi-directional hydraulic pump within the housing arranged to supply hydraulic fluid to the oscillating motor when rotated in one direction and to supply hydraulic fluid to the hydraulic device for releasing the brake when driven in the opposite direction. The device is capable of accepting a limited amount of fluid such that when the brake is released further output of the pump is blocked and the pump becomes a slip clutch to transmit the electric motor driving torque to the housing and cause it to rotate.

In another aspect of the invention a hydraulic transmission is provided including a positive displacement hydraulic pump having a pair of manifolds, one of which is inlet and the other of which is outlet depending upon the direction of rotation of the pump. A pair of one-way check valves each communicate a manifold with the sump for flow of fluid from the sump to the manifold. One manifold has an outlet port communicating with a hydraulic motor device having its discharge connected to the sump and the other manifold has an outlet connecting to a hydraulic device such that by reversing the direction of rotation of the hydraulic pump either of two devices may be selectively driven.

In a still further aspect of the invention, the outlet of the hydraulic pump leading to the device is bypassed to the sump through a pressure relief valve such that a the start of the spin operation the amount of torque to start the spin basket rotating will be limited.

In a further aspect, the valve has a valve member spaced from the axis of rotation and biased to the closed position by a spring the member being movable on a radial line so as to be subjected to centrifugal force whereby the opening pressure of the valve will change as the speed of rotation of the housing changes. In a preferred aspect, the valve member is biased against the spring by centrifugal force so that the opening pressure reduces with an increase in speed.

In a further aspect of the invention, a hydraulic pump is arranged to supply hydraulic fluid to either of a pair of hydraulic devices depending upon direction of rotation of the pump, each of the hydraulic devices having a requirement for an initial supply of hydraulic fluid commencing to transmit substantial forces such that an electric motor driving the pump in either direction starts with no or a minimum load thereon.

In a still further aspect, the transmission housing contains a sump between the pump housing and its outer walls and the pump inlet passages open into this sump ad- 4 jacent the bottom and close to the outer walls whereby the oil entering the pump is fully deaerated by centrifugal action on the hydraulic fluid.

OBI ECT S Another object of the invention is the provision of a new and improved hydraulic laundry machine transmission for driving either an agitator or a spin basket wherein the operation of either one or the other may be readily controlled by changing the direction of rotation of an electric motor. v

Another object of the invention is the provision of a new and improved hydraulic laundry machine transmission which does not require the use of electric solenoid operated valves or brakes.

Another object of the invention is the provision of a new and improved hydraulic laundry machine transmission which does not have any gears or clutches.

Another object of the invention is the provision of a new and improved laundry machine transmission which is a compact unitary device and may replace without change a present gear reducing mechanism and crank arm mechanisms.

Still another object of the invention is a provision of a new and improved hydraulic transmission for laundry machines and the like wherein all operating parts may be completely sealed in a single housing.

Another object of the invention is the provision of a new and improved hydraulic laundry machine transmission wherein de-energization of the electric driving motor automatically applies the brake to stop the spin basket from rotating. Another object of the invention is the provision of a new and improved laundry machine transmission wherein the maximum torque to turn the spin basket automatically decreases as the speed of rotation increases.

Still another object is the provision of means for automatically limiting the spin speed in the event of unbalance of clothes in the spin basket.

Another object is the provision of a spin driving arrangement for laundry machines which is arranged to slip readily but has a maximum efficiency of power transmission.

PREFERRED EMBODIMENT OF THE INVENTION The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in this specification in detail and illustrated in the accompanying drawings which form a part hereof and wherein:

FIG. 1 is a side cross-sectional view showing the transmission of the invention in operative relationship with the elements of a conventional laundry machine;

FIG. 2 is an enlarged cross-sectional view of the transmission of FIG. 1;

FIG. 3 is a partial cross-sectional view of FIG. 2 taken on the line 33 thereof and in effect is looking upwardly t0 the manifolds of the hydraulic pump and with portions of the pump below the section line illustrated in shadow lines for clarity;

FIG. 4 is a partial cross-sectional view of FIG. 2 taken on the line 44 looking upward on the vane type motor for driving the agitator and with portions below the section line shown in shadow lines for clarity;

FIG. 5 is a partial sectional view of FIG. 1 taken on the line 55 thereof;

FIG. 6 is a partial sectional view of an inlet valve taken on line 6-6 of FIG. 5; and

FIG. 7 is a partial sectional view taken on line 77 of FIG. 1 showing the agitator drive shaft and with the agitator omitted for clarity of illustration.

Referring now to the drawings wherein the showings are for the purposes of illustrating a preferred embodiment of the invention only and not for the purposes of limiting same. FIG. 1 shows somewhat schematically a laundry machine comprised of a tub A, a perforated spin basket B concentrically arranged in the tub A and adapted to be rotated and an agitator C concentrically arranged within the basket and arranged to be oscillated and agitate the clothes within the spin basket B. The machine also includes base D on which an electric drive motor E is mounted and a pivoted frictional support F for the tub A and its associated equipment including the transmission of the present invention.

This transmission is positioned immediately below the tub A and supports the spin basket B and agitator C. It is comprised generally of a housing H supported for rotation on a roller bearing 40 but restrained from rotation by a normally closed friction brake S and containing on the inside a hydraulic pump P, a first hydraulic motor M mechanically coupled to the agitator C and adapted to oscillate same when supplied with hydraulic fluid and a hydraulic device T for releasing the normally engaged brake S when supplied with hydraulic fluid. A relief valve V limits the torque transmitted to the housing H when the spin cycle starts or unbalance occurs.

LAUNDRY MACHINE The laundry machine per se forms no part of the present invention and is shown solely for the purpose of illustrating how the transmission of the present invention may be applied to such a machine. Thus tub A may take any known or desired shape as is required for the washing. Suitable means not shown may be provided for supplying water to or removing such water therefrom. The tub A as shown is supported on three legs 10 which extend downwardly to the movable member 11 of the pivoted support F. This movable member has a downwardly facing surface 12 in the shape of a segment of a sphere which mates with a similarly shaped upwardly facing surface 13 on the base D. A friction member 14 is positioned between these surfaces and three springs 16, one from each leg 10 to the base D, bias the tub A and transmission so that the axis thereof is normally vertical. All of this mechanism can move essentially horizontally in any direction with the center of the sphere being the pivot point. This frictional type support F is conventional in the art. It is to be noted that because of the frictional characteristics, energy is required to move the tub A horizontally and the amount of energy increases as the speed of spin increases. This horizontal movement compensates for unbalance during the spin cycle.

The basket B may also take any desired form or shape but is generally perforated so that the water may pass freely into and out of the basket so that the water in the clothing may be centrifuged thereout during the spin cycle. In another type machine, the basket walls may be solid and the water is spun over the top to separate it from the clothes. This basket is supported for rotation upon a hollow shaft 20 which passes downwardly through a water seal bearing 21 in the lower part of the tub A and terminates in and is rigidly fastened to a counterbore in an upwardly extending sleeve 22 forming part of the housing H.

The agitator C also may be of any desired shape or construction and is supported for oscillation on a shaft 23 positioned with hollow shaft 20 and extending upwardly beyond the upper end thereof where it is fastened to the agitator C in any desired manner, such as by a spline 24. This shaft 23 is rotatably supported in the shaft 20 by means of an upper bearing sleeve 25 pressed into the inside of a counterbore at the upper end of the shaft 20. The lower end of the shaft is supported by a sleeve bearing 26 supported in a slightly smaller counterbore in the upper part of housing H and extends therebelow where it is keyed to the vane piston 27 of the agitator motor M by means of a key 28. An O-ring 29 located immediately below this bearing 26 seals space 30 between shafts 20, 23 from the chamber of motor M. This space 30 is normally filled with grease.

BASE

The base D may likewise take any one of a number of different shapes but in the embodiment shown is in the shape of an inverted cup having vertically extending cylindrical sidewalls 32 and a horizontally extending base 33 which has a central opening 34 defined by an upwardly and inwardly curved portion 35 on which the upwardly facing surface 13 is formed. The lower edge of the vertical sidewalls 32 have an outwardly extending flange 36 which may have openings therethrough so that the base D may be fastened to the outer housing of the laundry machine (not shown).

The movable member 11 of the pivoted support F has a lateral portion 38 extending across and closing the opening 34 which portion 38 has a central opening through which a downwardly extending sleeve 39 forming part of the housing H extends and is rotatably supported therein by means of a roller bearing 40-. As shown the sleeve 39 has a downwardly facing shoulder resting on the inner race of the bearing 40. The bearing 40 is retained in position by means of a C-ring 42 fitting into a groove in a cylindrical flange 43 extending upwardly from the lateral portion 38 and locating the roller bearing 40 relative to the member 11.

The member 11 also has an upwardly extending cylindrical flange 44 outwardly of the flange 43 on the upper end of which is fastened by means of screws 45, a cylindrical ring 46 having an inwardly and upwardly extending flange 47 which as will appear forms the fixed member of the brake S.

This brake S is additionally comprised of a movable member 50 mounted and having at its outer edge a portion 51 which extends outwardly and downwardly at the same angle as the portion 47. A ring 52 of friction material is positioned between these angularly extending flanges 47, 51 and may be fastened to one or the other if desired. A bow spring 53 in the shape of a washer engages the underside of the flange 51 and is supported on the shaft 39 by means of a C-ring 54 engaged in a groove in the shaft 39. This bow spring 53 biases the angular portions 47, 51 against the friction material 52 so that the brake S is always in the normally engaged position.

MOTOR The electric motor E is the power source which powers the entire transmission unit. It may take any number of known forms but by virtue of the present invention may be of a type having a low starting torque. For example, a single phase AC motor of split phase type. Such a motor is much less expensive than a high starting torque motor conventionally used in laundry machines today. It may also be multispeed if desired.

In the preferred embodiment the motor E has a running winding and a starting winding 86 which is disconnected by a centrifugal switch 87 operatively associated with the shaft of the motor. One of these windings is connected to an alternating current source through a polarity reversing switch 88 so that depending upon the position of the switch the motor may be made to start in either direction. In the embodiment shown the motor E is mounted on the portion 33 of base D and its shaft 89 extends downwardly through an opening in wall 33. A pulley 91 mounted on shaft 89 drives a pulley 92 on shaft 75 through a v-belt 93. The relative sizes of the V pulleys are such that the speed of rotation of shaft 75 will be just slightly greater than the desired maximum spin speed of the basket B.

7 HOUSING The housing H may take any one of a number of different forms, but in the embodiment shown is generally in three portions, namely, an upper portion 60, a lower portion 61 and an intermediate portion 62 which in the embodiment shown forms the manifold plate for the pump P.

The upper portion 60 is generally in the shape of an inverted stemmed cup having generally vertically extending sidewalls 65, a horizontally extending base 66 and the upwardly extending sleeve 22 previously referred to. The outer portion of the base 66 is relatively thin but has a thickened portion 67 at the center which has a downwardly facing cylindrical recess 68 coaxial with the axis of shaft 23 which recess 68 forms the chamber for the agitator vane motor M.

The lower portion 61 in vertical cross-section is generally in the shape of a disc having a relatively thin outer portion 70 and the downwardly extending sleeve 39 at its center. The lower edge of the wall 65 abuts against outer portion 70 of 61 and is sealed thereto by means of an O-ring 69. The lower portion 61 also has a central upwardly extending portion 71 spaced from wall 65 to define a sump 74 generally in the shape of a ring around the outside of the housing H. Threaded plug 73 provides access to the sump 7-4.

The portion 71 has an upwardly facing cylindrical recess 72 which forms the chamber for the pump P. The axis of this recess or chamber 72 is offset from the axis of shaft 23 and drive shaft 75 which as shown extends downwardly and out of the lower end of the sleeve 39. This shaft 75 is journalled in the sleeve 39 by means of an upper sleeve bearing 76 and a lower sleeve bearing 77 suitably fixed on the inside of the shaft 39. An O-ring 78 below the lower end of the bearing engages the outer surface of the shaft 75 and provides a fluid seal.

The intermediate portion or manifold plate 62 is generally in the shape of a disc and its upper and lower surfaces 81, 82 are in abutting and sealing engagement with the downwardly and upwardly facing surfaces of the portions 67, 71.

PUMP

The pump P is a positive displacement device and may take any one of a number of different forms e.g., a reciprocating piston type pump, a rotating vane type pump or the like but the preferred embodiment is an internal geartype pump comprised of an externally toothed gear 100 keyed to the shaft 75 and an internally tooth ring gear 101 rotatably supported by the cylindrical surface of recess 72 on an axis slightly spaced from that of the gear. As is conventional the ring gear 101 has one tooth more than the internal gear 100 and the teeth of these gears are in sliding sealing engagement to provide a plurality of pumping chambers which progressively increase in volume after they pass a minimum volume point on the neutral axis of the gears to a point of maximum volume on the neutral axis 103 and then progressively decreases in volume until they reach the minimum volume point. Hydraulic fluid is thus sucked into and forced out of these chambers depending upon whether the volume is increasing or decreasing. It will be appreciated that when the direction of rotation of the pump is reversed, chambers which were increasing in volume will then decrease in volume and vice versa.

The lower surface 82 of the manifold plate 62 has two manifolds 105, 106 formed therein which are generally arcuate and are positioned a distance from the axis of the shaft such as to communicate with the chamber of the gears as they rotate. The arcuate ends of these manifolds are circumferentially spaced from each other so that the surface between the ends of the manifolds forms the pump lands 107, 108 located and generally symmetrical to the neutral axis 103. The entire portion of surface 82 facing the pump recess 72 and the upwardly facing surface 72a of recess 72 are in sliding and sealing engagement with the upper and lower surfaces of the gears to thus seal the chambers one from the other except when the manifolds overlap one or more chambers and they are in com munication.

The pump has another manifold 110 in surface 72a and so located that when the pump is rotating in a clockwise direction as viewed in FIG. 3 this manifold 110 will communicate with the decreasing volume chambers and becomes a discharge manifold. Manifolds 110 and 106 communicate with the same pump chambers.

When the pump rotates in the opposite direction, manifold 105 will become the discharge manifold and in accordance with the invention this manifold 105 communicates with the vane motor chamber 68 by means of passage 111 opening through the surface 81 defining the lower surface of chamber 68 for motor M.

In accordance with the invention hydraulic fluid can flow freely from the sump to each manifold through a pair of one-way flow actuated check valves, one for each manifold. Such valves and communicating passages are identical and only one will be described herein. Such valves and their communicating passages may take any one of a number of different forms but in the embodiment shown the surface 82 on the lower side of the manifold plate 62 has a short recess 115 extending from manifold 105 radially outwardly where it communicates with a vertically extending passage 116 in the lower portion of the housing. This passage 116 has a valve seat 117 formed adjacent the lower end thereof and a steel ball 118 rests thereagainst. The passage 116 continues downwardly to communicate with a passage 119 which extends radially outwardly to sump 74 at a point close to but spaced from the inner surface of wall 65 and at the bottom of sump 74. The spacing from wall 65 must be such that the inlet to passage 119 will always be submerged in hydraulic fluid even when the housing is rotating and the fluid in the sump is forced radially outwardly and upwardly along wall 65 by centrifugal force. An advantage of this is that the centrifugal force tends to separate any air entrained in the oil so that the danger of drawing air into the pump chamber is eliminated.

With the two one-way check valves, the pump inlet manifold will always be supplied with hydraulic fluid regardless of its direction of rotation.

AGITATOR MOTOR The agitator motor M may take any one of a number of different forms capable of producing the desired oscillating motion, e.g., a rotating motor or a reciprocating piston with motion translating mechanism but in the preferred embodiment is a vane type oscillating hydraulic motor. The motor as shown is comprised of the piston 27 made up generally of a central hub 126 and a vane 127. The vane 127 has a vertical groove on its outer radial end in which a steel roller 128 is loosely mounted. This roller slidingly and sealingly engages the cylindrical surface of recess 68 while the hub 126, vane 127 and roller 128 each have an axial length such as to sealingly and slidingly engage the upper and lower surfaces of the motor housing 68. The hub 126 is keyed to shaft 23 by means of key 28.

Various types of valves may be provided for shifting the high pressure from the pump P to either side of the vane 127 and for alternating such shift at a predetermined time. In the preferred embodiment a toggle action valve is provided positioned within the motor chamber and arranged so as to be directly actuated by the position of the vane and so arranged that the pressure forces on it will always shift it to one position or the other and hold it in such position.

In the preferred embodiment, the valve comprises a member 132 of a thickness such that its upper and lower surfaces are in sliding and sealing engagement with the upper and lower surfaces of the motor chamber 68. This member 132 is pivoted about a vertically extending axis 133 substantially spaced from the axis of rotation of the 9 shaft 23. On the line 134 between such axes, the port 111 communicating manifold 105 with the chamber 68' is located.

The valve member 132 is symmetrical about this line 134 to the axes and has a pair of sealing members 135 and 136 one on either side of the line 134 which are adapted to alternately sealingly engage the cylindrical surface of the recess 68 as the valve member pivots in one position to the other. Rollers 140 and 141 seal against hub 126. A pair of discharge ports 137 and 138 are provided in the lower edge of the wall 67 located one on either side of the line 134 and between the line 134 and the point of engagement of the members 135 and 136 with the cylindrical surface.

It is to be noted that the return passage from the ports 137 and 138 to the sump 74 are somewhat smaller than the size of the inlet port for the motor such that when fluid is being discharged through one of these ports there will be a slight amount of back pressure on the discharge of the motor.

The operation of this motor is fully described in my Pat. No. 3,242,703 issued Mar. 29, 1966, and Pat. No. 3,291,006 issued Dec. 13, 1966, and will not be further detailed herein.

THE NORMALLY ENGAGED BRAKE The normally engaged brake as heretofore indicated is comprised of fixed member 47 and movable member 51 with a friction member 52 positioned there'between and biased to the normally closed position by bow spring 53. This brake may be released by any one of a number of different means, e.g. an external mechanism, a solenoid, a hydraulic bellows such as described in Pat. No. 2,574,418, but in the preferred embodiment of the invention shown is comprised of a piston 175 generally in the shape of a ring extending upwardly from the portion 50 and slidably engaged in a correspondingly shaped cylinder 176 formed in the lower surface of the lower portion of the housing 61 which is coaxial with the axis of the shaft 75. A pair of O-rings 177, 178 on the inner and outer surfaces of the piston 175 seal the piston cylinder arrangement. The cylinder 176 communicates with the pump cavity through passage 110.

In operation when the pump rotates in a clockwise direction as indicated in FIG. 3, hydraulic fluid is discharged into the cylinder 176 to force the piston 175, portion 50 and member 51 downwardly against the force of spring 53. This releases the normally engaged brake S.

It will be noted that the area of the piston 175 is substantial in relation to the output volume of the pump P, such that when the pump is started to be rotated in a direcion which will supply hydraulic fluid to the cylinder 176, the increase of pressure in the cylinder 176 will be relatively slow and the pump P and motor E will have reached a substantial operating speed before the pressure in this cylinder 176 begins to build up to substantial amounts which would place a load on the motor E. Also, the area of the piston 175 is such that the spring 50 will be deflected with about 50 p.s.i. hydraulic pressure. In this manner the motor E starts in the spin direction under substantially no load.

Once the piston 175 has reached the end of its downward stroke, the cylinder 176 cannot accept any more hydraulic fluid. The outlet pressure of the pump P then rises very rapidly, such that the pump essentially locks and the rotational torque of the motor E is transmitted to the housing H and its begins to rotate.

To prevent the pressures from building up too rapidly, a pressure relief valve is provided. Such pressure relief valve in the embodiment shown is comprised of a radially extending passage 200 communicating with the passage 110 and having a valve member 201 slidable therein. The valve member 201 is biased to the closed position by means of a spring 202 biased at one end against a set screw 203 and at the other end against the valve member 201. The valve member 201 engages a valve seat 205. When the valve member 201 is moved to the right as viewed in FIG. 2 passage will be communicated with the sump through passage 206. Passage 207 is a bleed passage for the chamber 200 to enable the valve member 201 to move.

It will be noted that the valve member 201 is spaced from the axis of rotation and is movable on a radial line, and is biased to the closed position by spring 202. However when the housing H rotates the member 201 will be subjected to centrifugal forces which are in a direction opposite to the biasing force of spring 202. Thus when the housing H is stationary a greater pressure is required to move the valve member 201 to the open position than that required when the housing H is rotating.

This is an important feature of the present invention and the amount of centrifugal force for a given speed of rotation developed on the member 201 may be readily adjusted by controlling the distance of the member 201 from the axis of rotation, or by adjusting its mass, or both. In addition, the set screw 203 can control the biasing force of the spring 202.

OPERATION AGITATE To describe the operation of the transmission it will be assumed that the sump X and all chambers and passages in the housing are filled to a level such that the cavity of the agitate motor is at least only partially filled.

The switch 88 is placed in the agitate position and the motor E is energized and commences to rotate in a direction such as to rotate the pump P in a counterclockwise direction as viewed in FIG. 3. Fluid immediately flows into the increasing volume chambers of the pump and is discharged into the cavity of the motor M. At this point, as the cavity is at least only partially filled, there is no load on the pump and the motor can come up to a substantial speed before this motor cavity is filled and commences to drive vane piston 27 to move the agitator C. All during this time the brake S is engaged and the housing H is prevented from rotation. Accordingly, movement of the vane motor M forces the agitator C to oscillate.

The time interval for the pump to fill the agitator motor cavity varies from the maximum when the level of oil in the sump is below the lower surface of the motor cavity to a minimum when the level of the oil in the sump is such as to maintain the agitator motor cavity filled at all times.

OPERATIONSPIN When it is desired to cause the basket B to spin and centrifugally force the water out of the clothes, the switch 88 is placed in the spin position and the motor E energized in the opposite direction from the agitate direction such that the pump P is rotated in a clockwise direction as viewed in FIG. 3. When this occurs, fluid is sucked into the increasing volume chambers through its associated one-way check valve while the other check valve communicating with the increasing volume chambers is closed. The fluid is thus forced into the cylinder 176 and the piston is forced downwardly against the force of the bow spring 53 to disengage the normally engaged brake S. As the spring 53 is bent, the pressure is built up slowly in the cylinder 176. When the piston 175 has reached the limit of its downward stroke, the cylinder 176 will not accept any more fluid and in eifect the output of the pump P is blocked. At this point the output pressure of the pump builds up very rapidly and the torque of the motor E is transmitted through the pump P to the housing H. As the brake S is disengaged, the housing H commences to rotate on its bearing 40 and both the agitator C and spin basket B rotate therewith.

These two members have substantial inertia and the pressure in pump P builds up until it exceeds the opening pressure of the valve member 201. This member 201 moves to the right bypassing some of the fluid from the 1 1 pump back to the sump 74. This action limits the torque which can be transmitted to the housing H and gives a controlled acceleration of the spin of the basket B. As the speed of the basket comes up to the speed of rotation of shaft 75 and the pump P, the pressure tends to drop. However, it never drops to zero because of winda ge and other friction losses. There is thus always enough pressure to keep the piston 175 in its downward position and to maintain the "brake S disengaged. In this respect the area of the piston 175 and the force required to move the spring 53 must be so inter-related that considering windage losses and friction, enough pressure will always exist on the piston 175 to maintain the brake S in the disengaged position during the spin operation. In the embodiment of the invention as shown, the dimensions are such that the pressure required for this purpose is approximately 50 lbs. per square inch. I

If it be assumed that the clothes in the spin basket are not evenly arranged around its circumference but are so arranged that the rotating mass is unbalanced relative to the axis of rotation, the entire assemblage of tub, basket, agitator and transmission will move in an essentially horizontal direction with the pivot point being the center of the spherical surfaces 12 and 13. However, the springs 16 hold these surfaces in tight frictional engagement with the friction material 14 therebetween. A considerable amount of energy is dissipated in friction and as the spin speed increases, the amount of energy dissipated also increases. Thus, the pressure on the outlet of the pump P remains relatively high and will increase as the speed of rotation increases. However, at the same time the valve member 201 has an increasing centrifugal force thereon opposing the bias of the spring 202 and ultimately the pressure will rise high enough in relation to the spin speed that the valve member 201 will move to the open position bypassing some of the fluid from the pump back to the sump. At this point the speed of rotation of the basket will no longer increase. In effect the maximum speed of the basket is automatically limited in amounts inversely proportional to the amount of unbalance of clothes in the spin basket.

When it is desired to stop the spin operation, the motor E is deenergized. At this point the hydraulic pressure in the cylinder 176 drives the pump P as a motor for a short period of time and the piston 175 is forced upwardly by the spring 53 thus bringing the brake S back into its normally engaged position. The spin basket B and housing H are quickly braked to a stop.

The spring 53 is preferably one which requires a total force of approximately 300 lbs. to disengage the brake S. The area of the piston 175 is selected so that about 50 lbs. per square inch are required to disengage the brake. On the other hand the cracking pressure of the valve 201 is set to about 500 lbs. per square inch. At the maximum spin speed, the amount of pressure required to crack this valve is of course somewhat less as above described.

In the transmission described, and in the spin position, all frictional forces within the pump P and in the bearings also tend to drive the housing H to rotate with the result that excellent efficiency on the order of 98% is obtained and the only losses are a slight amount of fluid slippage within the pump P.

It has been found that if shaft 75 is rotated at 650 r.p.m. the rotational speed of the housing H will be on the order of 630 r.p.m.

The invention has been described with reference to the use of a reversible motor. Such an arrangement has proven to be extremely simple and effective in operation. It will be appreciated however that aspects of the invention are not necessarily limited to the use of a multi-direction motor. For example, a uni-directional motor could be employed with appropriate valving to direct the fiuid to the motor or block the output of the pump. It will also be appreciated that the vane motor M can have a conven- 12 tional rotating hydraulic motor substituted therefor suc that the transmission can provide rotation of the shafts 20, 23 either in the same direction, or in opposite directions and that by properly inter-relating the displacement of the motor M and the pump P, any desired speed of rotation of the shaft 23 relative to the speed of rotation of the shaft 20 can be obtained.

Certain details of construction and in particular pressure balancing of the internally toothed ring gear in its chamber have not been described herein and reference is made to my Pat. No. 3,242,703 and Pat. No. 3,291,006 which describe and claim the pressure balancing arrangement for the ring gear. Also a fuller description of many manifolding techniques may also be obtained in my earlier patents.

Having thus defined my invention, I claim:

1. A transmission for laundry machines of the agitate spin type comprising in combination a rotatable housing adapted to be operatively associated with a spin basket, a friction brake for restraining said housing from rotation when engaged, a hydraulic device associated with said brake operative when under pressure to release same when said housing is to be rotated, a motor within the housing and adapted to be operatively associated with an agitator, a bi-directional hydraulic pump within the housing having a pair of manifolds, one of which is an inlet manifold and the other one of which is an outlet manifold when the pump is rotating in one direction and vice versa when the pump is operating in the opposite direction, a sump, a pair of one-way check valves one communicating each manifold with the sump for fluid flow from the sump to the manifold, means communicating one of said manifolds with an inlet port on said motor and means communicating the other manifold with said device.

2. The transmission of claim 1 wherein a pressure relief valve communicates said device with the sump, said pressure relief valve having a substantially higher opening pressure than the pressure required to operate said device.

3. The transmission of claim 2 wherein said pressure relief valve includes a valve member movable on a radial line, spring means biasing said valve member radially inwardly to a closed position, said valve member being located at a point spaced from the axis of rotation of said housing whereby centrifugal force on said valve member creates a bias thereon in opposition to the spring bias.

4. A hydraulic transmission for laundry machines of the spin and agitate type comprised of a rotatable housing, said housing being comprised of an outer shell and an inner pump housing defining therebetween a sump, said pump having an inlet manifold and passage means communicating said inlet manifold with a lower radially outer portion of said sump.

5. The combination of claim 1 wherein said device is a piston cylinder arrangement.

6. The combination of claim 5 wherein said piston and cylinder are in the form of a ring coaxial with the axis of rotation.

7. The combination of claim 2 wherein said device releases said brake with a pressure on the order of 50 p.s.i. and said relief valve opens at a pressure in excess of 400 p.s.i.

8. A hydraulic laundry machine transmission for laundry machines of the agitate and spin type comprised of a rotatably supported housing, an oscillating motor therein and having an inlet port, a hydraulic pump therein having a pair of manifolds, means connecting one of said manifolds with said motor inlet port where by when said pump is rotated in one direction hydraulic fluid is supplied to said motor, means blocking the flow of fluid from said other manifold when the pump is rotated in the opposite direction, whereby said pump transmits torque to said housing, and friction brake means for selectively restrain ing said housing from rotation or permitting rotation of 13 same, hydraulic means actuated by the pressure of said blocked flow of fluid for releasing said brake means.

9. A transmission for laundry machines of the agitate spin type comprising in combination a rotatable housing adapted to be operatively associated with a spin basket, a normally engaged friction brake for restraining said housing from rotation when engaged, a motor associated with the agitator, a hydraulic pump within said housing, means within said housing selectively communicating said pump to said motor when said pump rotates in one direction and selectively blocking the discharge of said pump and releasing said brake when said pump rotates in the opposite direction.

References Cited UNITED STATES PATENTS Rubano.

Brundage 92121 Brundage 6053 XR Haas et al. 68-23 XR Kurtz 6823 Kurtz.

US. Cl. X.R. 

